Silicon breakthrough could make key microwave technology much cheaper and better

Atomic structure of an unstrained 3.1 nm [110] SiNW and corresponding electronic (band) structure. (a) Front view and side view of a 3.1 nm [110] SiNW under no strain. Five unit cells of SiNW are shown in the side view highlighting the canted SiH2 (silicon dihydride) units. (b) Graphical representation of finding secondary states for an electron in sub band 1 (B1) which scatters to sub band 3 (B3) assisted by LA phonons. Ideally the secondary states in B3 (shadowed strip) form a quasi-continuum. In simulation, this is limited by the resolution of discretizing the BZ along kz. (c) The same graphical example for scattering from B1 to all sub bands (B1, B2, B3 and B4) assisted by LO phonons. Here there is a limited number of secondary states with corresponding rates arranged in a table. (d) Band structure of the unstrained nanowire showing a direct bandgap value of Eg = 1.554 eV and an energy offset of ΔE = 131 meV. The first four conduction sub bands (numbered as S1, S2, S3 and S4) are selected to calculate all electron-phonon scattering events required by EMC simulation.

High-frequency microwaves convey motions in an extensive variety of gadgets, including the radar units police use to get speeders and crash shirking frameworks in autos.

The microwaves are normally created by gadgets called Gunn diodes, which exploit the extraordinary properties of costly and poisonous semiconductor materials, for example, gallium arsenide.

At the point when a voltage is connected to gallium arsenide and after that expanded, the electrical current going through it likewise increments – however just to a specific point. Past that point, the present declines, a peculiarity is known as the Gunn effect that outcomes in the outflow of microwaves.

Now, by using a powerful supercomputer Daryoush Shiri, a former Waterloo doctoral student, showed that the same effect could be achieved with silicon. He has discovered a way to generate microwaves with inexpensive silicon. ”

The new technology involves silicon nanowires so tiny it would take 100,000 of them bundled together to equal the thickness of a human hair. Using complex computers models, Shiri showed that if silicon nanowires were stretched as voltage was applied to them, the Gunn effect, and therefore the emission of microwaves, could be induced.

C.R. Selvakumar, an engineering professor at the University of Waterloo said, “Until now, this was considered impossible. The stretching mechanism could also act as a switch to turn the effect on and off, or vary the frequency of microwaves for a host of new applications that haven’t even been imagined yet.”

“Although, this hypothetical work is the first step in a development process that could lead to much cheaper, more flexible devices for the generation of microwaves. Now we will see where it goes, how it will ramify.”